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Kamble SA, Barale SS, Mohammed AA, Paymal SB, Naik NM, Sonawane KD. Structural insights into the potential binding sites of Cathepsin D using molecular modelling techniques. Amino Acids 2024; 56:33. [PMID: 38649596 PMCID: PMC11035400 DOI: 10.1007/s00726-023-03367-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 12/11/2023] [Indexed: 04/25/2024]
Abstract
Alzheimer's disease (AD) is the most prevalent type of dementia caused by the accumulation of amyloid beta (Aβ) peptides. The extracellular deposition of Aβ peptides in human AD brain causes neuronal death. Therefore, it has been found that Aβ peptide degradation is a possible therapeutic target for AD. CathD has been known to breakdown amyloid beta peptides. However, the structural role of CathD is not yet clear. Hence, for the purpose of gaining a deeper comprehension of the structure of CathD, the present computational investigation was performed using virtual screening technique to predict CathD's active site residues and substrate binding mode. Ligand-based virtual screening was implemented on small molecules from ZINC database against crystal structure of CathD. Further, molecular docking was utilised to investigate the binding mechanism of CathD with substrates and virtually screened inhibitors. Localised compounds obtained through screening performed by PyRx and AutoDock 4.2 with CathD receptor and the compounds having highest binding affinities were picked as; ZINC00601317, ZINC04214975 and ZINCC12500925 as our top choices. The hydrophobic residues Viz. Gly35, Val31, Thr34, Gly128, Ile124 and Ala13 help stabilising the CathD-ligand complexes, which in turn emphasises substrate and inhibitor selectivity. Further, MM-GBSA approach has been used to calculate binding free energy between CathD and selected compounds. Therefore, it would be beneficial to understand the active site pocket of CathD with the assistance of these discoveries. Thus, the present study would be helpful to identify active site pocket of CathD, which could be beneficial to develop novel therapeutic strategies for the AD.
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Affiliation(s)
- Subodh A Kamble
- Structural Bioinformatics Unit, Department of Biochemistry, Shivaji University, Kolhapur, M.S., 416004, India
| | - Sagar S Barale
- Department of Microbiology, Shivaji University, 416004, M.S., Kolhapur, India
| | - Ali Abdulmawjood Mohammed
- Structural Bioinformatics Unit, Department of Biochemistry, Shivaji University, Kolhapur, M.S., 416004, India
| | - Sneha B Paymal
- Department of Microbiology, Shivaji University, 416004, M.S., Kolhapur, India
| | - Nitin M Naik
- Department of Microbiology, Shivaji University, 416004, M.S., Kolhapur, India
| | - Kailas D Sonawane
- Structural Bioinformatics Unit, Department of Biochemistry, Shivaji University, Kolhapur, M.S., 416004, India.
- Department of Chemistry, Shivaji University, Kolhapur, M.S., 416004, India.
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2
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Zhao R. Exercise mimetics: a novel strategy to combat neuroinflammation and Alzheimer's disease. J Neuroinflammation 2024; 21:40. [PMID: 38308368 PMCID: PMC10837901 DOI: 10.1186/s12974-024-03031-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 01/25/2024] [Indexed: 02/04/2024] Open
Abstract
Neuroinflammation is a pathological hallmark of Alzheimer's disease (AD), characterized by the stimulation of resident immune cells of the brain and the penetration of peripheral immune cells. These inflammatory processes facilitate the deposition of amyloid-beta (Aβ) plaques and the abnormal hyperphosphorylation of tau protein. Managing neuroinflammation to restore immune homeostasis and decrease neuronal damage is a therapeutic approach for AD. One way to achieve this is through exercise, which can improve brain function and protect against neuroinflammation, oxidative stress, and synaptic dysfunction in AD models. The neuroprotective impact of exercise is regulated by various molecular factors that can be activated in the same way as exercise by the administration of their mimetics. Recent evidence has proven some exercise mimetics effective in alleviating neuroinflammation and AD, and, additionally, they are a helpful alternative option for patients who are unable to perform regular physical exercise to manage neurodegenerative disorders. This review focuses on the current state of knowledge on exercise mimetics, including their efficacy, regulatory mechanisms, progress, challenges, limitations, and future guidance for their application in AD therapy.
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Affiliation(s)
- Renqing Zhao
- College of Physical Education, Yangzhou University, Yangzhou, China.
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3
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Dias-Carvalho A, Sá SI, Carvalho F, Fernandes E, Costa VM. Inflammation as common link to progressive neurological diseases. Arch Toxicol 2024; 98:95-119. [PMID: 37964100 PMCID: PMC10761431 DOI: 10.1007/s00204-023-03628-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 10/12/2023] [Indexed: 11/16/2023]
Abstract
Life expectancy has increased immensely over the past decades, bringing new challenges to the health systems as advanced age increases the predisposition for many diseases. One of those is the burden of neurologic disorders. While many hypotheses have been placed to explain aging mechanisms, it has been widely accepted that the increasing pro-inflammatory status with advanced age or "inflammaging" is a main determinant of biological aging. Furthermore, inflammaging is at the cornerstone of many age-related diseases and its involvement in neurologic disorders is an exciting hypothesis. Indeed, aging and neurologic disorders development in the elderly seem to share some basic pathways that fundamentally converge on inflammation. Peripheral inflammation significantly influences brain function and contributes to the development of neurological disorders, including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Understanding the role of inflammation in the pathogenesis of progressive neurological diseases is of crucial importance for developing effective treatments and interventions that can slow down or prevent disease progression, therefore, decreasing its social and economic burden.
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Affiliation(s)
- Ana Dias-Carvalho
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313, Porto, Portugal.
- UCIBIO- Applied Molecular Biosciences Unit, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, 4050-313, Porto, Portugal.
| | - Susana Isabel Sá
- Unit of Anatomy, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal
- CINTESIS@RISE, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Félix Carvalho
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313, Porto, Portugal
- UCIBIO- Applied Molecular Biosciences Unit, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, 4050-313, Porto, Portugal
| | - Eduarda Fernandes
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313, Porto, Portugal
| | - Vera Marisa Costa
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313, Porto, Portugal.
- UCIBIO- Applied Molecular Biosciences Unit, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, 4050-313, Porto, Portugal.
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4
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Feng Y, Fan J, Cheng Y, Dai Q, Ma S. Stress regulates Alzheimer's disease progression via selective enrichment of CD8 + T cells. Cell Rep 2023; 42:113313. [PMID: 37858461 DOI: 10.1016/j.celrep.2023.113313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 08/25/2023] [Accepted: 10/04/2023] [Indexed: 10/21/2023] Open
Abstract
This study investigates stress's impact on Alzheimer's disease (AD) using male APP/PS1 transgenic mice. Negative stressors (chronic social defeat, restraint) and positive hedonia (environmental enrichment, EE) were applied. Stress worsens AD pathology, while EE slows progression. Brain RNA sequencing reveals interleukin-6 (IL-6) and IL-10 as key stress-related AD regulators. Flow cytometry shows that the CD8+/CD4+ T cell ratio shifts in response to stress exposure and EE. Stress exposure increases CD8+/CD4+ ratio, opposite to EE. Depletion and enrichment of CD8+ T cells both accelerate AD, indicating immune intervention's negative impact. Stress management and balanced immunity may aid AD therapy, highlighting novel potential treatment.
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Affiliation(s)
- Yilin Feng
- Tsinghua Shenzhen International Graduate School (SIGS), Tsinghua University, Shenzhen 518055, China; Tsinghua-Berkeley Shenzhen Institute (TBSI), Shenzhen 518055, China
| | - Jiaqi Fan
- Tsinghua Shenzhen International Graduate School (SIGS), Tsinghua University, Shenzhen 518055, China; Tsinghua-Berkeley Shenzhen Institute (TBSI), Shenzhen 518055, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China
| | - Yifan Cheng
- Tsinghua Shenzhen International Graduate School (SIGS), Tsinghua University, Shenzhen 518055, China; Tsinghua-Berkeley Shenzhen Institute (TBSI), Shenzhen 518055, China
| | - Qionghai Dai
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Shenzhen 518055, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China
| | - Shaohua Ma
- Tsinghua Shenzhen International Graduate School (SIGS), Tsinghua University, Shenzhen 518055, China; Tsinghua-Berkeley Shenzhen Institute (TBSI), Shenzhen 518055, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China.
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5
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Choi C, Kim H, Oh J, Park C, Kim M, Kim CS, Park J. DSCR1 deficiency ameliorates the Aβ pathology of Alzheimer's disease by enhancing microglial activity. Life Sci Alliance 2023; 6:6/2/e202201556. [PMID: 36450444 PMCID: PMC9713304 DOI: 10.26508/lsa.202201556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 11/17/2022] [Accepted: 11/21/2022] [Indexed: 12/02/2022] Open
Abstract
Microglial phagocytosis and clearance are important for the removal of amyloid-β (Aβ) plaques in Alzheimer's disease (AD). Chronic exposure of microglia to Aβ plaques leads to microglial metabolic dysfunction, and dysregulation of microglia can accelerate the deposition of Aβ plaques and cause learning and memory impairment. Thus, regulating microglial Aβ clearance is crucial for the development of therapeutics for AD-related dementia. Here, Down syndrome critical region 1 (DSCR1) deficiency ameliorated Aβ plaque deposition in the 5xFAD mouse model of AD by altering microglial activity; however, the Aβ synthesis pathway was not affected. DSCR1 deficiency improved spatial learning and memory impairment in 5xFAD mice. Furthermore, DSCR1-deficient microglia exhibited accelerated lysosomal degradation of Aβ after phagocytosis, and BV2 cells with stable knockdown of DSCR1 demonstrated enhanced lysosomal activity. RNA-sequencing analysis showed that the transcriptional signatures associated with responses to IFN-γ were significantly up-regulated in DSCR1-knockdown BV2 cells treated with Aβ. Our data strongly suggest that DSCR1 is a critical mediator of microglial degradation of amyloid plaques and a new potential microglial therapeutic target in AD.
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Affiliation(s)
- Chiyeol Choi
- Department of Biological Sciences, College of Information and Bioengineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hyerin Kim
- Department of Biological Sciences, College of Information and Bioengineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Jiyoung Oh
- Department of Biological Sciences, College of Information and Bioengineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Chanho Park
- Department of Biological Sciences, College of Information and Bioengineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Min Kim
- Department of Biological Sciences, College of Information and Bioengineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Chu-Sook Kim
- Department of Biological Sciences, College of Information and Bioengineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Jiyoung Park
- Department of Biological Sciences, College of Information and Bioengineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
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6
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Plaque attack: Microglia have hard feelings toward amyloid-β. Neuron 2023; 111:1-2. [PMID: 36603547 DOI: 10.1016/j.neuron.2022.11.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Classically, microglia recognize and internalize amyloid-β (Aβ) via it binding to cell surface receptors. In this issue of Neuron, Hu et al.1 report that microglia "feel" and internalize Aβ plaques using the stiffness-sensing channel Piezo1. This could allow new approaches to treating Alzheimer's disease.
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Bivona G, Iemmolo M, Agnello L, Lo Sasso B, Gambino CM, Giglio RV, Scazzone C, Ghersi G, Ciaccio M. Microglial Activation and Priming in Alzheimer's Disease: State of the Art and Future Perspectives. Int J Mol Sci 2023; 24:ijms24010884. [PMID: 36614325 PMCID: PMC9820926 DOI: 10.3390/ijms24010884] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/29/2022] [Accepted: 12/30/2022] [Indexed: 01/05/2023] Open
Abstract
Alzheimer's Disease (AD) is the most common cause of dementia, having a remarkable social and healthcare burden worldwide. Amyloid β (Aβ) and protein Tau aggregates are disease hallmarks and key players in AD pathogenesis. However, it has been hypothesized that microglia can contribute to AD pathophysiology, as well. Microglia are CNS-resident immune cells belonging to the myeloid lineage of the innate arm of immunity. Under physiological conditions, microglia are in constant motion in order to carry on their housekeeping function, and they maintain an anti-inflammatory, quiescent state, with low expression of cytokines and no phagocytic activity. Upon various stimuli (debris, ATP, misfolded proteins, aggregates and pathogens), microglia acquire a phagocytic function and overexpress cytokine gene modules. This process is generally regarded as microglia activation and implies that the production of pro-inflammatory cytokines is counterbalanced by the synthesis and the release of anti-inflammatory molecules. This mechanism avoids excessive inflammatory response and inappropriate microglial activation, which causes tissue damage and brain homeostasis impairment. Once the pathogenic stimulus has been cleared, activated microglia return to the naïve, anti-inflammatory state. Upon repeated stimuli (as in the case of Aβ deposition in the early stage of AD), activated microglia shift toward a less protective, neurotoxic phenotype, known as "primed" microglia. The main characteristic of primed microglia is their lower capability to turn back toward the naïve, anti-inflammatory state, which makes these cells prone to chronic activation and favours chronic inflammation in the brain. Primed microglia have impaired defence capacity against injury and detrimental effects on the brain microenvironment. Additionally, priming has been associated with AD onset and progression and can represent a promising target for AD treatment strategies. Many factors (genetics, environmental factors, baseline inflammatory status of microglia, ageing) generate an aberrantly activated phenotype that undergoes priming easier and earlier than normally activated microglia do. Novel, promising targets for therapeutic strategies for AD have been sought in the field of microglia activation and, importantly, among those factors influencing the baseline status of these cells. The CX3CL1 pathway could be a valuable target treatment approach in AD, although preliminary findings from the studies in this field are controversial. The current review aims to summarize state of the art on the role of microglia dysfunction in AD pathogenesis and proposes biochemical pathways with possible targets for AD treatment.
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Affiliation(s)
- Giulia Bivona
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, University of Palermo, 90133 Palermo, Italy
| | - Matilda Iemmolo
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, 90128 Palermo, Italy
| | - Luisa Agnello
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, University of Palermo, 90133 Palermo, Italy
| | - Bruna Lo Sasso
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, University of Palermo, 90133 Palermo, Italy
- Department of Laboratory Medicine, University Hospital “P.Giaccone”, 90127 Palermo, Italy
| | - Caterina Maria Gambino
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, University of Palermo, 90133 Palermo, Italy
- Department of Laboratory Medicine, University Hospital “P.Giaccone”, 90127 Palermo, Italy
| | - Rosaria Vincenza Giglio
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, University of Palermo, 90133 Palermo, Italy
- Department of Laboratory Medicine, University Hospital “P.Giaccone”, 90127 Palermo, Italy
| | - Concetta Scazzone
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, University of Palermo, 90133 Palermo, Italy
| | - Giulio Ghersi
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, 90128 Palermo, Italy
| | - Marcello Ciaccio
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, University of Palermo, 90133 Palermo, Italy
- Department of Laboratory Medicine, University Hospital “P.Giaccone”, 90127 Palermo, Italy
- Correspondence: ; Tel.: +39-09-1655-3296
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8
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Li JQ, Zhong XL, Song JH, Chi S, Xie AM, Tan L, Yu JT. Associations Between TREML2 Gene Variants and Alzheimer's Disease: Biomarkers, Neuroimage, and Cognition. J Alzheimers Dis 2023; 96:1555-1563. [PMID: 37980675 DOI: 10.3233/jad-230936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
BACKGROUND Recent genetic research identified a protective factor against late-onset Alzheimer's disease (AD) in Caucasians, a variant called rs3747742-C in the TREML2 gene. However, the roles of other TREML2 variants in AD have not been fully explored. OBJECTIVE We conducted a focused analysis of 16 TREML2 variants, examining their connection to AD by studying their correlation with cerebrospinal fluid (CSF) proteins, neuroimage, and cognition in the Alzheimer's Disease Neuroimaging Initiative database (ADNI). METHODS A multiple linear regression model was utilized to estimate potential associations between TREML2 genotypes and various endophenotypes in the entire ADNI sample at baseline, with age, gender, years of education, and APOE ɛ4 status included as covariates. To examine changes in clinical outcomes over time, linear mixed-effects models were employed. RESULTS We found that the SNP rs17328707-A was associated with higher ADNI-VS scores, smaller ventricles, and larger middle temporal volume at baseline. The SNP rs6915083-G was linked to lower CSF t-tau and p-tau levels, and higher CSF Aβ levels. The SNP rs9394766-G was associated with a smaller hippocampus and larger ventricles at baseline. In longitudinal cohorts, the rs6915083-G SNP was associated with changes in ADNI-MEM and ADNI-EF scores, as well as the rate of hippocampal and middle temporal atrophy. CONCLUSION Our findings reveal that TREML2 gene variants have different effects on AD. Two variants are protective, while one may be a risk factor. This enhances our understanding of AD genetics and could guide future research and personalized treatments.
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Affiliation(s)
- Jie-Qiong Li
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Xiao-Ling Zhong
- Department of Neurology, Affiliated Qingdao Central Hospital of Qingdao University, Qingdao Cancer Hospital, Qingdao, China
| | - Jing-Hui Song
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Song Chi
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - An-Mu Xie
- Department of Neurology, the Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Lan Tan
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, Qingdao, Shandong, China
| | - Jin-Tai Yu
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, Qingdao, Shandong, China
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de Lima IB, Ribeiro FM. The Implication of Glial Metabotropic Glutamate Receptors in Alzheimer's Disease. Curr Neuropharmacol 2023; 21:164-182. [PMID: 34951388 PMCID: PMC10190153 DOI: 10.2174/1570159x20666211223140303] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 12/05/2021] [Accepted: 12/16/2021] [Indexed: 11/22/2022] Open
Abstract
Alzheimer's disease (AD) was first identified more than 100 years ago, yet aspects pertaining to its origin and the mechanisms underlying disease progression are not well known. To this date, there is no therapeutic approach or disease-modifying drug that could halt or at least delay disease progression. Until recently, glial cells were seen as secondary actors in brain homeostasis. Although this view was gradually refuted and the relevance of glial cells for the most diverse brain functions such as synaptic plasticity and neurotransmission was vastly proved, many aspects of its functioning, as well as its role in pathological conditions, remain poorly understood. Metabotropic glutamate receptors (mGluRs) in glial cells were shown to be involved in neuroinflammation and neurotoxicity. Besides its relevance for glial function, glutamatergic receptors are also central in the pathology of AD, and recent studies have shown that glial mGluRs play a role in the establishment and progression of AD. AD-related alterations in Ca2+ signalling, APP processing, and Aβ load, as well as AD-related neurodegeneration, are influenced by glial mGluRs. However, different types of mGluRs play different roles, depending on the cell type and brain region that is being analysed. Therefore, in this review, we focus on the current understanding of glial mGluRs and their implication in AD, providing an insight for future therapeutics and identifying existing research gaps worth investigating.
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Affiliation(s)
- Izabella B.Q. de Lima
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Fabíola M. Ribeiro
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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10
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Zhong G, Long H, Zhou T, Liu Y, Zhao J, Han J, Yang X, Yu Y, Chen F, Shi S. Blood-brain barrier Permeable nanoparticles for Alzheimer's disease treatment by selective mitophagy of microglia. Biomaterials 2022; 288:121690. [PMID: 35965114 DOI: 10.1016/j.biomaterials.2022.121690] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 05/30/2022] [Accepted: 07/18/2022] [Indexed: 11/30/2022]
Abstract
Current treatments for Alzheimer's disease (AD) that focus on inhibition of Aβ aggregation failed to show effectiveness in people who already had Alzheimer's symptoms. Strategies that synergistically exert neuroprotection and alleviation of oxidative stress could be a promising approach to correct the pathological brain microenvironment. Based on the key roles of microglia in modulation of AD microenvironment, we describe here the development of Prussian blue/polyamidoamine (PAMAM) dendrimer/Angiopep-2 (PPA) nanoparticles that can regulate the mitophagy of microglia as a potential AD treatment. PPA nanoparticles exhibit superior blood-brain barrier (BBB) permeability and exert synergistic effects of ROS scavenging and restoration of mitochondrial function of microglia. PPA nanoparticles effectively reduce neurotoxic Aβ aggregate and rescue the cognitive functions in APP/PS1 model mice. Together, our data suggest that these multifunctional dendrimer nanoparticles exhibit efficient neuroprotection and microglia modulation and can be exploited as a promising approach for the treatment of AD.
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Affiliation(s)
- Gang Zhong
- Department of Neurology, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, 530007, China; Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Huiping Long
- Department of Neurology, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, 530007, China
| | - Tian Zhou
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Yisi Liu
- Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Jianping Zhao
- Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Jinyu Han
- Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Xiaohu Yang
- Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Yin Yu
- Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
| | - Fei Chen
- Center for Materials Synthetic Biology, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
| | - Shengliang Shi
- Department of Neurology, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, 530007, China.
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11
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Kim SJ, Russell AE, Wang W, Gemoets DE, Sarkar SN, Simpkins JW, Brown CM. miR-146a Dysregulates Energy Metabolism During Neuroinflammation. J Neuroimmune Pharmacol 2022; 17:228-241. [PMID: 34028667 PMCID: PMC8611101 DOI: 10.1007/s11481-021-09999-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 05/13/2021] [Indexed: 12/29/2022]
Abstract
Alzheimer's disease (AD) and other neurodegenerative diseases are characterized by chronic neuroinflammation and a reduction in brain energy metabolism. An important role has emerged for small, non-coding RNA molecules known as microRNAs (miRNAs) in the pathophysiology of many neurodegenerative disorders. As epigenetic regulators, miRNAs possess the capacity to regulate and fine tune protein production by inhibiting translation. Several miRNAs, which include miR-146a, are elevated in the brain, CSF, and plasma of AD patients. miR-146a participates in pathways that regulate immune activation and has several mRNA targets which encode for proteins involved in cellular energy metabolism. An additional role for extracellular vesicles (EVs) has also emerged in the progression AD, as EVs can transfer functionally active proteins and RNAs from diseased to healthy cells. In the current study, we exposed various cell types present within the CNS to immunomodulatory molecules and observed significant upregulation of miR-146a expression, both within cells and within their secreted EVs. Further, we assessed the effects of miR-146a overexpression on bioenergetic function in primary rat glial cells and found significant reductions in oxidative phosphorylation and glycolysis. Lastly, we correlated miR-146a expression levels within various regions of the AD brain to disease staging and found significant, positive correlations. These novel results demonstrate that the modulation of miR-146a in response to neuroinflammatory stimuli may mediate the loss of mitochondrial integrity and function in cells, thereby contributing to the progression of beta-amyloid and tau pathology in the AD brain. Multiple inflammatory stimuli can upregulate miRNA-146a expression within neurons, mixed glial cells, and brain endothelial cells, which is either retained within these cells or released from them as extracellular vesicle cargo. The upregulation of miR-146a disrupts cellular bioenergetics in mixed glial cells. This mechanism may play a critical role in the neuroinflammatory response observed during Alzheimer's disease.
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Affiliation(s)
- Sujung Jun Kim
- Department of Physiology and Pharmacology, School of Medicine, West Virginia University, Morgantown, WV, United States, 26506
| | - Ashley E. Russell
- Department of Neuroscience and Center for Basic and Translational Stroke Research, School of Medicine, West Virginia University, Morgantown, WV, United States, 26506,Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States, 26506
| | - Wei Wang
- Department of Neuroscience and Center for Basic and Translational Stroke Research, School of Medicine, West Virginia University, Morgantown, WV, United States, 26506
| | - Darren E. Gemoets
- Department of Biostatistics, School of Public Health, West Virginia University, Morgantown, WV United States 26506
| | - Saumyendra N. Sarkar
- Department of Physiology and Pharmacology, School of Medicine, West Virginia University, Morgantown, WV, United States, 26506
| | - James W. Simpkins
- Department of Physiology and Pharmacology, School of Medicine, West Virginia University, Morgantown, WV, United States, 26506,Department of Neuroscience and Center for Basic and Translational Stroke Research, School of Medicine, West Virginia University, Morgantown, WV, United States, 26506,Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States, 26506
| | - Candice M. Brown
- Department of Neuroscience and Center for Basic and Translational Stroke Research, School of Medicine, West Virginia University, Morgantown, WV, United States, 26506,Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, United States, 26506
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12
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Blood-brain barrier leakage in Alzheimer's disease: From discovery to clinical relevance. Pharmacol Ther 2022; 234:108119. [PMID: 35108575 PMCID: PMC9107516 DOI: 10.1016/j.pharmthera.2022.108119] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/14/2022] [Accepted: 01/18/2022] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease (AD) is the most common form of dementia. AD brain pathology starts decades before the onset of clinical symptoms. One early pathological hallmark is blood-brain barrier dysfunction characterized by barrier leakage and associated with cognitive decline. In this review, we summarize the existing literature on the extent and clinical relevance of barrier leakage in AD. First, we focus on AD animal models and their susceptibility to barrier leakage based on age and genetic background. Second, we re-examine barrier dysfunction in clinical and postmortem studies, summarize changes that lead to barrier leakage in patients and highlight the clinical relevance of barrier leakage in AD. Third, we summarize signaling mechanisms that link barrier leakage to neurodegeneration and cognitive decline in AD. Finally, we discuss clinical relevance and potential therapeutic strategies and provide future perspectives on investigating barrier leakage in AD. Identifying mechanistic steps underlying barrier leakage has the potential to unravel new targets that can be used to develop novel therapeutic strategies to repair barrier leakage and slow cognitive decline in AD and AD-related dementias.
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13
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Jethava KP, Prakash P, Manchanda P, Arora H, Chopra G. One Scaffold, Different Organelle Sensors: pH-Activable Fluorescent Probes for Targeting Live Microglial Cell Organelles. Chembiochem 2022; 23:e202100378. [PMID: 34585478 PMCID: PMC9835645 DOI: 10.1002/cbic.202100378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/28/2021] [Indexed: 01/14/2023]
Abstract
Targeting live cell organelles is essential for imaging, understanding, and controlling specific biochemical processes. Typically, fluorescent probes with distinct structural scaffolds are used to target specific cell organelles. Here, we have designed a modular one-step synthetic strategy using a common reaction intermediate to develop new lysosomal, mitochondrial, and nucleus-targeting pH-activable fluorescent probes that are all based on a single boron dipyrromethane scaffold. The divergent cell organelle targeting was achieved by synthesizing probes with specific functional group changes to the central scaffold resulting in differential fluorescence and pKa . Specifically, we show that the functional group transformation of the same scaffold influences cellular localization and specificity of pH-activable fluorescent probes in live primary microglial cells with pKa values ranging from ∼3.2-6.0. We introduce a structure-organelle-relationship (SOR) framework to target nuclei (NucShine), lysosomes (LysoShine), and mitochondria (MitoShine) in live microglia. This work will result in future applications of SOR beyond imaging to target and control organelle-specific biochemical processes in disease-specific models.
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Affiliation(s)
- Krupal P. Jethava
- Department of Chemistry, Purdue University, West Lafayette, IN 47907 (USA)
| | - Priya Prakash
- Department of Chemistry, Purdue University, West Lafayette, IN 47907 (USA)
| | - Palak Manchanda
- Department of Chemistry, Purdue University, West Lafayette, IN 47907 (USA)
| | - Harshit Arora
- Department of Chemistry, Purdue University, West Lafayette, IN 47907 (USA)
| | - Gaurav Chopra
- Department of Chemistry, Purdue University, West Lafayette, IN 47907 (USA),Purdue University, Purdue Institute for Drug Discovery, West Lafayette, IN 47907 (USA),Purdue University, Purdue Institute for Integrative Neuroscience, West Lafayette, IN 47907 (USA),Purdue University, Purdue Institute for Inflammation, Immunology and Infectious Disease, West Lafayette, IN 47907 (USA),Purdue University, Purdue Center for Cancer Research, West Lafayette, IN 47907 (USA),Purdue University, Integrative Data Science Initiative, West Lafayette, IN 47907 (USA)
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14
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Pons V, Rivest S. Targeting Systemic Innate Immune Cells as a Therapeutic Avenue for Alzheimer Disease. Pharmacol Rev 2022; 74:1-17. [PMID: 34987086 DOI: 10.1124/pharmrev.121.000400] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/13/2021] [Indexed: 12/12/2022] Open
Abstract
Alzheimer disease (AD) is the first progressive neurodegenerative disease worldwide, and the disease is characterized by an accumulation of amyloid in the brain and neurovasculature that triggers cognitive decline and neuroinflammation. The innate immune system has a preponderant role in AD. The last decade, scientists focused their efforts on therapies aiming to modulate innate immunity. The latter is of great interest, since they participate to the inflammation and phagocytose the amyloid in the brain and blood vessels. We and others have developed pharmacological approaches to stimulate these cells using various ligands. These include toll-like receptor 4, macrophage colony stimulating factor, and more recently nucleotide-binding oligomerization domain-containing 2 receptors. This review will discuss the great potential to take advantage of the innate immune system to fight naturally against amyloid β accumulation and prevent its detrimental consequence on brain functions and its vascular system. SIGNIFICANCE STATEMENT: The focus on amyloid β removal from the perivascular space rather than targeting CNS plaque formation and clearance represents a new direction with a great potential. Small molecules able to act at the level of peripheral immunity would constitute a novel approach for tackling aberrant central nervous system biology, one of which we believe would have the potential of generating a lot of interest.
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Affiliation(s)
- Vincent Pons
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, 2705 Laurier Boul., Québec City, QC G1V 4G2, Canada
| | - Serge Rivest
- Neuroscience Laboratory, CHU de Québec Research Center and Department of Molecular Medicine, Faculty of Medicine, Laval University, 2705 Laurier Boul., Québec City, QC G1V 4G2, Canada
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15
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Streit WJ, Rotter J, Winter K, Müller W, Khoshbouei H, Bechmann I. Droplet Degeneration of Hippocampal and Cortical Neurons Signifies the Beginning of Neuritic Plaque Formation. J Alzheimers Dis 2021; 85:1701-1720. [PMID: 34958037 DOI: 10.3233/jad-215334] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Neuritic plaques contain neural and microglial elements, and amyloid-β protein (Aβ), but their pathogenesis remains unknown. OBJECTIVE Elucidate neuritic plaque pathogenesis. METHODS Histochemical visualization of hyperphosphorylated-tau positive (p-tau+) structures, microglia, Aβ, and iron. RESULTS Disintegration of large projection neurons in human hippocampus and neocortex presents as droplet degeneration: pretangle neurons break up into spheres of numerous p-tau+ droplets of various sizes, which marks the beginning of neuritic plaques. These droplet spheres develop in the absence of colocalized Aβ deposits but once formed become encased in diffuse Aβ with great specificity. In contrast, neurofibrillary tangles often do not colocalize with Aβ. Double-labelling for p-tau and microglia showed a lack of microglial activation or phagocytosis of p-tau+ degeneration droplets but revealed massive upregulation of ferritin in microglia suggesting presence of high levels of free iron. Perl's Prussian blue produced positive staining of microglia, droplet spheres, and Aβ plaque cores supporting the suggestion that droplet degeneration of pretangle neurons in the hippocampus and cortex represents ferroptosis, which is accompanied by the release of neuronal iron extracellularly. CONCLUSION Age-related iron accumulation and ferroptosis in the CNS likely trigger at least two endogenous mechanisms of neuroprotective iron sequestration and chelation, microglial ferritin expression and Aβ deposition, respectively, both contributing to the formation of neuritic plaques. Since neurofibrillary tangles and Aβ deposits colocalize infrequently, tangle formation likely does not involve release of neuronal iron extracellularly. In human brain, targeted deposition of Aβ occurs specifically in response to ongoing ferroptotic droplet degeneration thereby producing neuritic plaques.
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Affiliation(s)
- Wolfgang J Streit
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, USA
| | - Jonas Rotter
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Karsten Winter
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Wolf Müller
- Department of Neuropathology, Leipzig University, Leipzig, Germany
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, USA
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Leipzig, Germany
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16
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Ngwa C, Qi S, Mamun AA, Xu Y, Sharmeen R, Liu F. Age and sex differences in primary microglia culture: A comparative study. J Neurosci Methods 2021; 364:109359. [PMID: 34537225 DOI: 10.1016/j.jneumeth.2021.109359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 08/27/2021] [Accepted: 09/13/2021] [Indexed: 01/02/2023]
Abstract
BACKGROUND Microglia play a central role in neuroinflammation in various CNS diseases.Neonatal microglial culture has been extensively used to in vitro study microglial activation; however, as many neuroinflammatory diseases occur in the elderly, the neonatal microglial culture may not fully replicate the aged microglial activity seen in these diseases. NEW METHOD Primary microglia from both 18-24-month-old and P0-P4 C57BL/6 mice were cultured simultaneously. Morphology and activation profiles of the two age groups of microglia were examined following ischemic stimulation, by ELISA, RT-PCR, live microscopy, immunocytochemistry, and Western blotting. RESULTS We showed that aged microglia had larger cell bodies, more cytoplasmic inclusions, and enhanced phagocytosis than neonatal microglia. Cytokine production in these cells exhibited heterogeneity either after or before ischemic stimulation. The baseline expression of microglial marker CD11b was significantly higher in aged vs. neonatal cells; ischemic stimulation increased the expression in neonatal vs. aged microglia only in males but not in females. COMPARISON WITH EXISTING METHODS Previous primary microglia cultures have been limited to using neonatal/adult cells. This method is complementary to exiting methods and works for aged microglia, and does not suffer from potential limitations due to filtering artifacts. The protocol renders microglial culture no need for meningeal/hippocampal removal prior to brain tissue dissociation, and compares microglia between males vs. females, and between the aged vs. neonates. CONCLUSIONS We concluded that neonatal microglial culture is not appropriate for those in vitro studies that mimic the neuroinflammatory central nervous system disorders occurring in the elderly, in which case the aged microglial culture should be applied, and sex differences should be considered.
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Affiliation(s)
- Conelius Ngwa
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Shaohua Qi
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Abdullah Al Mamun
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Yan Xu
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Romana Sharmeen
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Fudong Liu
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
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17
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Dyne E, Prakash PS, Li J, Yu B, Schmidt TL, Huang S, Kim MH. Mild magnetic nanoparticle hyperthermia promotes the disaggregation and microglia-mediated clearance of beta-amyloid plaques. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2021; 34:102397. [PMID: 33857686 DOI: 10.1016/j.nano.2021.102397] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 03/18/2021] [Indexed: 12/19/2022]
Abstract
The formation of beta-amyloid (Aβ) plaques is a classical hallmark of Alzheimer's disease (AD) that is associated with the promotion of neuroinflammation and subsequent neurotoxicity. Given the limited therapeutic options for targeting and clearing Aβ plaques in AD, there is an urgent need to develop effective approaches to reduce plaque accumulation. The objective of this study was to validate mild magnetic nanoparticle (MNP) hyperthermia technology as a strategy to clear Aβ deposits and determine the impact on microglia functionality. Our results demonstrated that the heating of MNPs localized to Aβ aggregates upon exposure to high frequency alternating magnetic field (AMF) was sufficient to disrupt Aβ plaques, resulting in its fragmentation. Importantly, this could facilitate the phagocytic clearance of Aβ as well as attenuate pro-inflammatory responses by human microglial cells. Our results support the feasibility of mild MNP/AMF hyperthermia as a new strategy for reducing beta-amyloid burdens in Alzheimer's disease.
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Affiliation(s)
- Eric Dyne
- School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Praneetha Sundar Prakash
- School of Biomedical Sciences, Kent State University, Kent, OH, USA; Department of Physics, Kent State University, Kent, OH, USA
| | - Junfeng Li
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH, USA
| | - Bing Yu
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Thorsten-Lars Schmidt
- School of Biomedical Sciences, Kent State University, Kent, OH, USA; Department of Physics, Kent State University, Kent, OH, USA
| | - Songping Huang
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH, USA
| | - Min-Ho Kim
- School of Biomedical Sciences, Kent State University, Kent, OH, USA; Department of Biological Sciences, Kent State University, Kent, OH, USA.
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18
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Leng F, Edison P. Neuroinflammation and microglial activation in Alzheimer disease: where do we go from here? Nat Rev Neurol 2021; 17:157-172. [PMID: 33318676 DOI: 10.1038/s41582-020-00435-y] [Citation(s) in RCA: 1261] [Impact Index Per Article: 420.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2020] [Indexed: 12/17/2022]
Abstract
Alzheimer disease (AD) is the most common form of neurodegenerative disease, estimated to contribute 60-70% of all cases of dementia worldwide. According to the prevailing amyloid cascade hypothesis, amyloid-β (Aβ) deposition in the brain is the initiating event in AD, although evidence is accumulating that this hypothesis is insufficient to explain many aspects of AD pathogenesis. The discovery of increased levels of inflammatory markers in patients with AD and the identification of AD risk genes associated with innate immune functions suggest that neuroinflammation has a prominent role in the pathogenesis of AD. In this Review, we discuss the interrelationships between neuroinflammation and amyloid and tau pathologies as well as the effect of neuroinflammation on the disease trajectory in AD. We specifically focus on microglia as major players in neuroinflammation and discuss the spatial and temporal variations in microglial phenotypes that are observed under different conditions. We also consider how these cells could be modulated as a therapeutic strategy for AD.
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Affiliation(s)
- Fangda Leng
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Paul Edison
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK.
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19
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Jorge L, Martins R, Canário N, Xavier C, Abrunhosa A, Santana I, Castelo-Branco M. Investigating the Spatial Associations Between Amyloid-β Deposition, Grey Matter Volume, and Neuroinflammation in Alzheimer's Disease. J Alzheimers Dis 2021; 80:113-132. [PMID: 33523050 PMCID: PMC8075404 DOI: 10.3233/jad-200840] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background: It has been proposed that amyloid-β (Aβ) plays a causal role in Alzheimer’s disease (AD) by triggering a series of pathologic events—possibly including neuroinflammation—which culminate in progressive brain atrophy. However, the interplay between the two pathological molecular events and how both are associated with neurodegeneration is still unclear. Objective: We aimed to estimate the spatial inter-relationship between neurodegeneration, neuroinflammation and Aβ deposition in a cohort of 20 mild AD patients and 17 healthy controls (HC). Methods: We resorted to magnetic resonance imaging to measure cortical atrophy, using the radiotracer 11C-PK11195 PET to measure neuroinflammation levels and 11C-PiB PET to assess Aβ levels. Between-group comparisons were computed to explore AD-related changes in the three types of markers. To examine the effects of each one of the molecular pathologic mechanisms on neurodegeneration we computed: 1) ANCOVAs with the anatomic data, controlling for radiotracer uptake differences between groups and 2) voxel-based multiple regression analysis between-modalities. In addition, associations in anatomically defined regions of interests were also investigated. Results: We found significant differences between AD and controls in the levels of atrophy, neuroinflammation, and Aβ deposition. Associations between Aβ aggregation and brain atrophy were detected in AD in a widely distributed pattern, whereas associations between microglia activation and structural measures of neurodegeneration were restricted to few anatomically regions. Conclusion: In summary, Aβ deposition, as opposed to neuroinflammation, was more associated with cortical atrophy, suggesting a prominent role of Aβ in neurodegeneration at a mild stage of the AD.
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Affiliation(s)
- Lília Jorge
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Ricardo Martins
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Nádia Canário
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Carolina Xavier
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Antero Abrunhosa
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Isabel Santana
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,Department of Neurology, Coimbra University Hospital, Coimbra, Portugal
| | - Miguel Castelo-Branco
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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20
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Streit WJ, Khoshbouei H, Bechmann I. The Role of Microglia in Sporadic Alzheimer's Disease. J Alzheimers Dis 2020; 79:961-968. [PMID: 33361603 DOI: 10.3233/jad-201248] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Microglia constitute the brain's immune system and their involvement in Alzheimer's disease has been discussed. Commonly, and in line with the amyloid/neuroinflammation cascade hypothesis, microglia have been portrayed as potentially dangerous immune effector cells thought to be overactivated by amyloid and producing neurotoxic inflammatory mediators that lead to neurofibrillary degeneration. We disagree with this theory and offer as an alternative the microglial dysfunction theory stating that microglia become impaired in their normally neuroprotective roles because of aging, i.e., they become senescent and aging neurons degenerate because they lack the needed microglial support for their survival. Thus, while the amyloid cascade theory relies primarily on genetic data, the dysfunction theory incorporates aging as a critical etiological factor. Aging is the greatest risk factor for the sporadic (late-onset) and most common form of Alzheimer's disease, where fully penetrant genetic mutations are absent. In this review, we lay out and discuss the human evidence that supports senescent microglial dysfunction and conflicts with the amyloid/neuroinflammation idea.
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Affiliation(s)
- Wolfgang J Streit
- Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | | | - Ingo Bechmann
- Anatomical Institute, University of Leipzig, Leipzig, Germany
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21
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Therapeutic potential of mangiferin in the treatment of various neuropsychiatric and neurodegenerative disorders. Neurochem Int 2020; 143:104939. [PMID: 33346032 DOI: 10.1016/j.neuint.2020.104939] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 11/02/2020] [Accepted: 12/12/2020] [Indexed: 12/19/2022]
Abstract
Xanthones are important chemical class of bioactive products that confers therapeutic benefits. Of several xanthones, mangiferin is known to be distributed widely across several fruits, vegetables and medicinal plants. Mangiferin has been shown to exert neuroprotective effects in both in-vitro and in-vivo models. Mangiferin attenuates cerebral infarction, cerebral edema, lipid peroxidation (MDA), neuronal damage, etc. Mangiferin further potentiate levels of endogenous antioxidants to confer protection against the oxidative stress inside the neurons. Mangiferin is involved in the regulation of various signaling pathways that influences the production and levels of proinflammatory cytokines in brain. Mangiferin cosunteracted the neurotoxic effect of amyloid-beta, MPTP, rotenone, 6-OHDA etc and confer protection to neurons. These evidence suggested that the mangiferin may be a potential therapeutic strategy for the treatment of various neurological disorders. The present review demonstrated the pharmacodynamics-pharmacokinetics of mangiferin and neurotherapeutic potential in several neurological disorders with underlying mechanisms.
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22
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Brown MR, Radford SE, Hewitt EW. Modulation of β-Amyloid Fibril Formation in Alzheimer's Disease by Microglia and Infection. Front Mol Neurosci 2020; 13:609073. [PMID: 33324164 PMCID: PMC7725705 DOI: 10.3389/fnmol.2020.609073] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 11/03/2020] [Indexed: 01/06/2023] Open
Abstract
Amyloid plaques are a pathological hallmark of Alzheimer's disease. The major component of these plaques are highly ordered amyloid fibrils formed by amyloid-β (Aβ) peptides. However, whilst Aβ amyloid fibril assembly has been subjected to detailed and extensive analysis in vitro, these studies may not reproduce how Aβ fibrils assemble in the brain. This is because the brain represents a highly complex and dynamic environment, and in Alzheimer's disease multiple cofactors may affect the assembly of Aβ fibrils. Moreover, in vivo amyloid plaque formation will reflect the balance between the assembly of Aβ fibrils and their degradation. This review explores the roles of microglia as cofactors in Aβ aggregation and in the clearance of amyloid deposits. In addition, we discuss how infection may be an additional cofactor in Aβ fibril assembly by virtue of the antimicrobial properties of Aβ peptides. Crucially, by understanding the roles of microglia and infection in Aβ amyloid fibril assembly it may be possible to identify new therapeutic targets for Alzheimer's disease.
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Affiliation(s)
- Madeleine R Brown
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Sheena E Radford
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Eric W Hewitt
- School of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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23
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Wang Y, Leppert A, Tan S, van der Gaag B, Li N, Schultzberg M, Hjorth E. Maresin 1 attenuates pro-inflammatory activation induced by β-amyloid and stimulates its uptake. J Cell Mol Med 2020; 25:434-447. [PMID: 33225628 PMCID: PMC7810927 DOI: 10.1111/jcmm.16098] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 10/13/2020] [Accepted: 10/29/2020] [Indexed: 12/15/2022] Open
Abstract
Alzheimer's disease (AD) is the most common dementia, characterized by pathological accumulation of β‐amyloid (Aβ) and hyperphosphorylation of tau protein, together with a damaging chronic inflammation. The lack of effective treatments urgently warrants new therapeutic strategies. Resolution of inflammation, associated with beneficial and regenerative activities, is mediated by specialized pro‐resolving lipid mediators (SPMs) including maresin 1 (MaR1). Decreased levels of MaR1 have been observed in AD brains. However, the pro‐resolving role of MaR1 in AD has not been fully investigated. In the present study, human monocyte‐derived microglia (MdM) and a differentiated human monocyte cell line (THP‐1 cells) exposed to Aβ were used as models of AD neuroinflammation. We have studied the potential of MaR1 to inhibit pro‐inflammatory activation of Aβ and assessed its ability to stimulate phagocytosis of Aβ42. MaR1 inhibited the Aβ42‐induced increase in cytokine secretion and stimulated the uptake of Aβ42 in both MdM and differentiated THP‐1 cells. MaR1 was also found to decrease chemokine secretion and reduce the associated increase in the activation marker CD40. Activation of kinases involved in transduction of inflammation was not affected by MaR1, but the activity of nuclear factor (NF)‐κB was decreased. Our data show that MaR1 exerts effects that indicate a pro‐resolving role in the context of AD and thus presents itself as a potential therapeutic target for AD.
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Affiliation(s)
- Ying Wang
- Department of Neurobiology, Care Sciences & Society, Division of Neurogeriatrics, Karolinska Institutet, Solna, Sweden
| | - Axel Leppert
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Shuai Tan
- Department of Medicine, Clinical Pharmacology Group, Karolinska University Hospital, Solna, Sweden
| | - Bram van der Gaag
- Department of Neurobiology, Care Sciences & Society, Division of Neurogeriatrics, Karolinska Institutet, Solna, Sweden
| | - Nailin Li
- Department of Medicine, Clinical Pharmacology Group, Karolinska University Hospital, Solna, Sweden
| | - Marianne Schultzberg
- Department of Neurobiology, Care Sciences & Society, Division of Neurogeriatrics, Karolinska Institutet, Solna, Sweden
| | - Erik Hjorth
- Department of Neurobiology, Care Sciences & Society, Division of Neurogeriatrics, Karolinska Institutet, Solna, Sweden
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24
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Xu CJ, Wang JL, Jing-Pan, Min-Liao. Tph2 Genetic Ablation Contributes to Senile Plaque Load and Astrogliosis in APP/PS1 Mice. Curr Alzheimer Res 2020; 16:219-232. [PMID: 30827242 DOI: 10.2174/1567205016666190301110110] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/20/2018] [Accepted: 01/11/2019] [Indexed: 01/06/2023]
Abstract
BACKGROUND Amyloid-β (Aβ) accumulation plays a critical role in the pathogenesis of Alzheimer's disease (AD) lesions. Deficiency of Serotonin signaling recently has been linked to the increased Aβ level in transgenic mice and humans. In addition, tryptophan hydroxylase-2 (Tph2), a second tryptophan hydroxylase isoform, controls brain serotonin synthesis. However, it remains to be determined that whether Tph2 deficient APP/PS1mice affect the formation of Aβ plaques in vivo. METHODS Both quantitative and qualitative immunochemistry methods, as well as Congo red staining were used to evaluate the Aβ load and astrogliosis in these animals. RESULTS we studied alterations of cortex and hippocampus in astrocytes and senile plaques by Tph2 conditional knockout (Tph2 CKO) AD mice from 6-10 months of age. Using Congo red staining and immunostained with Aβ antibody, we showed that plaques load or plaques numbers significantly increased in Tph2 CKO experimental groups at 8 to 10 months old, compared to wild type (WT) group, respectively. Using GFAP+ astrocytes immunofluorescence method, we found that the density of GFAP+ astrocytes markedly enhanced in Tph2 CKO at 10 months. We showed Aβ plaques co-localized autophagic markers LC3 and p62. Nevertheless, we did not observe any co-localization between GFAP+ astrocytes and autophagic markers, but detected the co-localization between βIII-tubulin+ neurons and autophagic markers. CONCLUSION Overall, our work provides the preliminary evidence in vivo that Tph2 plays a role in amyloid plaques generation.
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Affiliation(s)
- Chao-Jin Xu
- Department of Histology & Embryology, School of Basic Medical Science, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Jun-Ling Wang
- Centre for Reproductive Medicine, Affiliated Hospital 1 of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China
| | - Jing-Pan
- Department of Histology & Embryology, School of Basic Medical Science, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Min-Liao
- Department of Histology & Embryology, School of Basic Medical Science, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
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Pomilio C, Gorojod RM, Riudavets M, Vinuesa A, Presa J, Gregosa A, Bentivegna M, Alaimo A, Alcon SP, Sevlever G, Kotler ML, Beauquis J, Saravia F. Microglial autophagy is impaired by prolonged exposure to β-amyloid peptides: evidence from experimental models and Alzheimer's disease patients. GeroScience 2020; 42:613-632. [PMID: 31975051 DOI: 10.1007/s11357-020-00161-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/16/2020] [Indexed: 01/17/2023] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the presence of misfolded proteins, amyloid-β (Aβ) aggregates, and neuroinflammation in the brain. Microglial cells are key players in the context of AD, being capable of releasing cytokines in response to Aβ and degrading aggregated proteins by mechanisms involving the ubiquitin-proteasome system and autophagy. Here, we present in vivo and in vitro evidence showing that microglial autophagy is affected during AD progression. PDAPPJ20 mice-murine model of AD-exhibited an accumulation of the autophagy receptor p62 and ubiquitin+ aggregates in Iba1+ microglial cells close to amyloid deposits in the hippocampus. Moreover, cultured microglial BV-2 cells showed an enhanced autophagic flux during a 2-h exposure to fibrillar Aβ, which was decreased if the exposure was prolonged to 24 h, a condition analogous to the chronic exposure to Aβ in the human pathology. The autophagic impairment was also associated with lysosomal damage, depicted by membrane permeabilization as shown by the presence of the acid hydrolase cathepsin-D in cytoplasm and altered LysoTracker staining. These results are compatible with microglial exhaustion caused by pro-inflammatory conditions and persistent exposure to aggregated Aβ peptides. In addition, we found LC3-positive autophagic vesicles accumulated in phagocytic CD68+ microglia in human AD brain samples, suggesting defective autophagy in microglia of AD brain. Our results indicate that the capacity of microglia to degrade Aβ and potentially other proteins through autophagy may be negatively affected as the disease progresses. Preserving autophagy in microglia thus emerges as a promising approach for treating AD. Graphical abstract.
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Affiliation(s)
- Carlos Pomilio
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental (IBYME), CONICET, Obligado 2490, 1428, Buenos Aires, Argentina
| | - Roxana M Gorojod
- Departmento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IQUIBICEN, CONICET, Buenos Aires, Argentina
| | - Miguel Riudavets
- FLENI, Instituto de Investigaciones Neurológicas Dr Raúl Carrea, Buenos Aires, Argentina
| | - Angeles Vinuesa
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental (IBYME), CONICET, Obligado 2490, 1428, Buenos Aires, Argentina
| | - Jessica Presa
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental (IBYME), CONICET, Obligado 2490, 1428, Buenos Aires, Argentina
| | - Amal Gregosa
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental (IBYME), CONICET, Obligado 2490, 1428, Buenos Aires, Argentina
| | - Melisa Bentivegna
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental (IBYME), CONICET, Obligado 2490, 1428, Buenos Aires, Argentina
| | - Agustina Alaimo
- Departmento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IQUIBICEN, CONICET, Buenos Aires, Argentina
| | - Soledad Porte Alcon
- Departmento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IQUIBICEN, CONICET, Buenos Aires, Argentina
| | - Gustavo Sevlever
- FLENI, Instituto de Investigaciones Neurológicas Dr Raúl Carrea, Buenos Aires, Argentina
| | - Monica L Kotler
- Departmento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IQUIBICEN, CONICET, Buenos Aires, Argentina
| | - Juan Beauquis
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental (IBYME), CONICET, Obligado 2490, 1428, Buenos Aires, Argentina
| | - Flavia Saravia
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental (IBYME), CONICET, Obligado 2490, 1428, Buenos Aires, Argentina.
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El Hajj H, Savage JC, Bisht K, Parent M, Vallières L, Rivest S, Tremblay MÈ. Ultrastructural evidence of microglial heterogeneity in Alzheimer's disease amyloid pathology. J Neuroinflammation 2019; 16:87. [PMID: 30992040 PMCID: PMC6469225 DOI: 10.1186/s12974-019-1473-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 04/01/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is the most common neurodegenerative disease, characterized by the deposition of extracellular fibrillar amyloid β (fΑβ) and the intracellular accumulation of neurofibrillary tangles. As AD progresses, Aβ drives a robust and prolonged inflammatory response via its recognition by microglia, the brain's immune cells. Microglial reactivity to fAβ plaques may impair their normal surveillance duties, facilitating synaptic loss and neuronal death, as well as cognitive decline in AD. METHODS In the current study, we performed correlative light, transmission, and scanning electron microscopy to provide insights into microglial structural and functional heterogeneity. We analyzed microglial cell bodies and processes in areas containing fAβ plaques and neuronal dystrophy, dystrophy only, or appearing healthy, among the hippocampus CA1 of 14-month-old APPSwe-PS1Δe9 mice versus wild-type littermates. RESULTS Our quantitative analysis revealed that microglial cell bodies in the AD model mice were larger and displayed ultrastructural signs of cellular stress, especially nearby plaques. Microglial cell bodies and processes were overall less phagocytic in AD model mice. However, they contained increased fibrillar materials and non-empty inclusions proximal to plaques. Microglial cell bodies and processes in AD model mice also displayed reduced association with extracellular space pockets that contained debris. In addition, microglial processes in healthy subregions of AD model mice encircled synaptic elements more often compared with plaque-associated processes. These observations in mice were qualitatively replicated in post-mortem hippocampal samples from two patients with AD (Braak stage 5). CONCLUSION Together, our findings identify at the ultrastructural level distinct microglial transformations common to mouse and human in association with amyloid pathology.
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Affiliation(s)
- Hassan El Hajj
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
| | - Julie C. Savage
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
| | - Kanchan Bisht
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
| | - Martin Parent
- Département de psychiatrie et de neurosciences, Faculté de médecine, Université Laval, Quebec, QC Canada
- CERVO Brain Research Center, Quebec, QC Canada
| | - Luc Vallières
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Quebec, QC Canada
| | - Serge Rivest
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Quebec, QC Canada
| | - Marie-Ève Tremblay
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Quebec, QC Canada
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Galloway DA, Phillips AEM, Owen DRJ, Moore CS. Phagocytosis in the Brain: Homeostasis and Disease. Front Immunol 2019; 10:790. [PMID: 31040847 PMCID: PMC6477030 DOI: 10.3389/fimmu.2019.00790] [Citation(s) in RCA: 183] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 03/26/2019] [Indexed: 12/28/2022] Open
Abstract
Microglia are resident macrophages of the central nervous system and significantly contribute to overall brain function by participating in phagocytosis during development, homeostasis, and diseased states. Phagocytosis is a highly complex process that is specialized for the uptake and removal of opsonized and non-opsonized targets, such as pathogens, apoptotic cells, and cellular debris. While the role of phagocytosis in mediating classical innate and adaptive immune responses has been known for decades, it is now appreciated that phagocytosis is also critical throughout early neural development, homeostasis, and initiating repair mechanisms. As such, modulating phagocytic processes has provided unexplored avenues with the intent of developing novel therapeutics that promote repair and regeneration in the CNS. Here, we review the functional consequences that phagocytosis plays in both the healthy and diseased CNS, and summarize how phagocytosis contributes to overall pathophysiological mechanisms involved in brain injury and repair.
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Affiliation(s)
- Dylan A Galloway
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Alexandra E M Phillips
- Division of Brain Sciences, Department of Medicine Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - David R J Owen
- Division of Brain Sciences, Department of Medicine Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - Craig S Moore
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
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Yao XC, Xue X, Zhang HT, Zhu MM, Yang XW, Wu CF, Yang JY. Pseudoginsenoside‐F11 alleviates oligomeric β‐amyloid‐induced endosome‐lysosome defects in microglia. Traffic 2018; 20:61-70. [DOI: 10.1111/tra.12620] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 10/26/2018] [Accepted: 10/26/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Xue C. Yao
- Department of PharmacologyShenyang Pharmaceutical University Shenyang PR China
| | - Xue Xue
- State Key Laboratory of Medicinal Chemical Biology, College of PharmacyNankai University Tianjin PR China
| | - Hao T. Zhang
- Department of PharmacologyShenyang Pharmaceutical University Shenyang PR China
| | - Ming M. Zhu
- Department of PharmacologyShenyang Pharmaceutical University Shenyang PR China
| | - Xiao W. Yang
- Department of PharmacologyShenyang Pharmaceutical University Shenyang PR China
| | - Chun F. Wu
- Department of PharmacologyShenyang Pharmaceutical University Shenyang PR China
| | - Jing Y. Yang
- Department of PharmacologyShenyang Pharmaceutical University Shenyang PR China
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29
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Ugolini F, Lana D, Nardiello P, Nosi D, Pantano D, Casamenti F, Giovannini MG. Different Patterns of Neurodegeneration and Glia Activation in CA1 and CA3 Hippocampal Regions of TgCRND8 Mice. Front Aging Neurosci 2018; 10:372. [PMID: 30483118 PMCID: PMC6243135 DOI: 10.3389/fnagi.2018.00372] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/26/2018] [Indexed: 01/24/2023] Open
Abstract
We investigated the different patterns of neurodegeneration and glia activation in CA1 and CA3 hippocampal areas of TgCRND8 mice. The main feature of this transgenic model is the rapid development of the amyloid pathology, which starts already at 3 months of age. We performed immunohistochemical analyses to compare the different sensibility of the two hippocampal regions to neurodegeneration. We performed qualitative and quantitative evaluations by fluorescence immunohistochemistry with double or triple staining, followed by confocal microscopy and digital image analysis in stratum pyramidale (SP) and stratum radiatum (SR) of CA1 and CA3, separately. We evaluated time-dependent Aβ plaques deposition, expression of inflammatory markers, as well as quantitative and morphological alterations of neurons and glia in transgenic mice at 3 (Tg 3M) and 6 (Tg 6M) months of age, compared to WT mice. In CA1 SR of Tg 6M mice, we found significantly more Medium and Large plaques than in CA3. The pattern of neurodegeneration and astrocytes activation was different in the two areas, indicating higher sensitivity of CA1. In the CA1 SP of Tg 6M mice, we found signs of reactive astrogliosis, such as increase of astrocytes density in SP, increase of GFAP expression in SR, and elongation of astrocytes branches. We found also common patterns of glia activation and neurodegenerative processes in CA1 and CA3 of Tg 6M mice: significant increase of total and reactive microglia density in SP and SR, increased expression of TNFα, of iNOS, and IL1β in astrocytes and increased density of neurons-astrocytes-microglia triads. In CA1 SP, we found decrease of volume and number of pyramidal neurons, paralleled by increase of apoptosis, and, consequently, shrinkage of CA1 SP. These data demonstrate that in TgCRND8 mice, the responses of neurons and glia to neurodegenerative patterns induced by Aβ plaques deposition is not uniform in the two hippocampal areas, and in CA1 pyramidal neurons, the higher sensitivity may be related to the different plaque distribution in this area. All these modifications may be at the basis of memory loss, the peculiar symptom of AD, which was demonstrated in this transgenic mouse model of Aβ deposition, even at early stages.
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Affiliation(s)
- Filippo Ugolini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Daniele Lana
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Pamela Nardiello
- Department of Neuroscience, Psychology, Drug Research and Child Health, NEUROFARBA, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Daniele Nosi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Daniela Pantano
- Department of Neuroscience, Psychology, Drug Research and Child Health, NEUROFARBA, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Fiorella Casamenti
- Department of Neuroscience, Psychology, Drug Research and Child Health, NEUROFARBA, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Maria Grazia Giovannini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
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Streit WJ, Braak H, Del Tredici K, Leyh J, Lier J, Khoshbouei H, Eisenlöffel C, Müller W, Bechmann I. Microglial activation occurs late during preclinical Alzheimer's disease. Glia 2018; 66:2550-2562. [PMID: 30417428 DOI: 10.1002/glia.23510] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/18/2018] [Accepted: 07/18/2018] [Indexed: 01/10/2023]
Abstract
Sporadic Alzheimer's disease (AD) is marked by a lengthy preclinical phase during which patients are nonsymptomatic but show pathology in variable manifestations. Whether or not neuroinflammation occurs in such nondemented individuals is unknown. We evaluated the medial temporal lobe of 66 nondemented subjects, aged 42-93, in terms of tau pathology, Aβ deposition, and microglial activation. We show that 100% of subjects had neurofibrillary degeneration (NFD), 35% had Aβ deposits, and 8% revealed microglial activation in individuals where early amyloid formation was apparent by Congo Red staining. Amyloid-induced neuroinflammatory clusters of Iba1, CD68, and ferritin-positive microglia were evident in the immediate vicinity of aggregated Aβ. Microglia in the adjacent neuropil were nonactivated. Thus, neuroinflammation in AD represents a highly localized phagocyte reaction, essentially a foreign body response, geared toward removal of insoluble Aβ. Because clustered microglia in some amyloid plaques were dystrophic and ferritin-positive, we hypothesize that these cells were exhausted by their attempts to remove the aggregated, insoluble Aβ. Our findings show that the sequence of pathologic events in AD begins with tau pathology, followed by Aβ deposition, and then by microglial activation. Because only 8% of our subjects revealed all three hallmark pathologic features, we propose that these nondemented individuals were near the threshold of transitioning from nonsymptomatic to symptomatic disease. The onset of neuroinflammation in AD may thus represent a tipping point in AD pathogenesis. Our study suggests that the role of microglia in AD pathogenesis entails primarily the attempted removal of potentially toxic, extracellular material.
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Affiliation(s)
- Wolfgang J Streit
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida
| | - Heiko Braak
- Clinical Neuroanatomy (Department of Neurology), Center for Biomedical Research, University of Ulm, Ulm, Germany
| | - Kelly Del Tredici
- Clinical Neuroanatomy (Department of Neurology), Center for Biomedical Research, University of Ulm, Ulm, Germany
| | - Judith Leyh
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Julia Lier
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida
| | | | - Wolf Müller
- Department of Neuropathology, Leipzig University, Leipzig, Germany
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Leipzig, Germany
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31
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Lowry JR, Klegeris A. Emerging roles of microglial cathepsins in neurodegenerative disease. Brain Res Bull 2018; 139:144-156. [DOI: 10.1016/j.brainresbull.2018.02.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 01/23/2018] [Accepted: 02/13/2018] [Indexed: 01/21/2023]
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32
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Lysosomal enzyme tripeptidyl peptidase 1 destabilizes fibrillar Aβ by multiple endoproteolytic cleavages within the β-sheet domain. Proc Natl Acad Sci U S A 2018; 115:1493-1498. [PMID: 29378960 DOI: 10.1073/pnas.1719808115] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Accumulation of amyloid-beta (Aβ), which is associated with Alzheimer's disease, can be caused by excess production or insufficient clearance. Because of its β-sheet structure, fibrillar Aβ is resistant to proteolysis, which would contribute to slow degradation of Aβ plaques in vivo. Fibrillar Aβ can be internalized by microglia, which are the scavenger cells of the brain, but the fibrils are degraded only slowly in microglial lysosomes. Cathepsin B is a lysosomal protease that has been shown to proteolyze fibrillar Aβ. Tripeptidyl peptidase 1 (TPP1), a lysosomal serine protease, possesses endopeptidase activity and has been shown to cleave peptides between hydrophobic residues. Herein, we demonstrate that TPP1 is able to proteolyze fibrillar Aβ efficiently. Mass spectrometry analysis of peptides released from fibrillar Aβ digested with TPP1 reveals several endoproteolytic cleavages including some within β-sheet regions that are important for fibril formation. Using molecular dynamics simulations, we demonstrate that these cleavages destabilize fibrillar β-sheet structure. The demonstration that TPP1 can degrade fibrillar forms of Aβ provides insight into the turnover of fibrillar Aβ and may lead to new therapeutic methods to increase degradation of Aβ plaques.
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Torika N, Asraf K, Apte RN, Fleisher-Berkovich S. Candesartan ameliorates brain inflammation associated with Alzheimer's disease. CNS Neurosci Ther 2018; 24:231-242. [PMID: 29365370 DOI: 10.1111/cns.12802] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 12/05/2017] [Accepted: 12/24/2017] [Indexed: 01/08/2023] Open
Abstract
AIMS Alzheimer's disease (AD) pathology is associated with brain inflammation involving microglia and astrocytes. The renin-angiotensin system contributes to brain inflammation associated with AD pathology. This study aimed to investigate the role of candesartan, an angiotensin II type 1 receptor blocker, in modulation of glial functions associated with AD. METHODS Focusing on the role of candesartan in glial inflammation, we evaluated inflammatory mediators' levels, secreted by lipopolysaccharide-induced microglia following candesartan treatment. Also, short-term intranasal candesartan effects on amyloid burden and microglial activation were investigated in 5 familial AD mice. RESULTS Candesartan showed anti-inflammatory effects and shifted microglial activation toward a more neuroprotective phenotype. Candesartan decreased the lipopolysaccharide-induced nitric oxide synthase and cyclooxygenase-2 expression levels, which was accompanied by an induction of arginase-1 expression levels and enhanced Aβ1-42 uptake by microglia. Moreover, intranasally administered candesartan to AD mice model significantly reduced the amyloid burden and microglia activation in the hippocampus. CONCLUSIONS These results thus shed light on the neuroprotective role of candesartan in the early stage of AD, which might relate to modulation of microglial activation states.
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Affiliation(s)
- Nofar Torika
- Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Keren Asraf
- Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Ron N Apte
- Department of Microbiology and Immunology, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Sigal Fleisher-Berkovich
- Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beersheba, Israel
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Pharmacodynamics in Alzheimer's disease model rats of a bifunctional peptide with the potential to accelerate the degradation and reduce the toxicity of amyloid β-Cu fibrils. Acta Biomater 2018; 65:327-338. [PMID: 29111371 DOI: 10.1016/j.actbio.2017.10.039] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/26/2017] [Accepted: 10/26/2017] [Indexed: 12/14/2022]
Abstract
The accumulation of the extracellular β-amyloid (Aβ) aggregates with metal ions in conjunction with reactive oxygen species (ROS) is closely related to the pathogenesis of Alzheimer's disease (AD). Accounting on Cu ions chelating of our previously designed bifunctional peptide GGHRYYAAFFARR (GR) as well as Aβ-Cu fibrils (fAβ-Cu) dissociation potentials, we report herein an efficient route to synthetically minimize ROS toxicity and degrade fAβ-Cu. It is worth mentioning that GR combines the metal chelating agent GGH and β-sheet breaker RYYAAFFARR (RR). The in vitro results have showed that GR disassociates fAβ-Cu into smaller fragments (sAβ-Cu, 150-200 nm), easily assimilated by PC12 cell and subsequently degraded in the lysosomes; GR can also suppress the ROS generated by fAβ-Cu. The viability of PC12 cell treated with fAβ-Cu has increased, from 38% to about 70% after administration of GR, overwhelming the GGH chelator (46%) and single functional peptide RR (48%). The in vivo results indicated that GR has efficiently reduced Aβ deposition, ameliorated neurologic changes and rescued memory loss, thus, enhancing the cognitive and spatial memory in a AD rat model. This study confirms the superior effect of GR and paves the way toward its future employment in large scale AD treatment. STATEMENT OF SIGNIFICANCE We have focused on accelerating the degradation of fAβ-Cu as well as synthetically reducing the ROS toxicity by GR, and, consequently, its benefits in vivo. The bifunctional peptide GR can not only disaggregate fAβ-Cu into smaller fragments to facilitate uptake and degradation by PC12 cell, but also suppresses the ROS generated by fAβ-Cu. Thus, the viability of PC12 cell treated with fAβ-Cu has increased from 38% to 70% after GR administration, overwhelming GGH (46%) and RR (48%). The in vivo studies have revealed that GR improves the spatial memory ability and reduce the amount of senile plaques within brain of AD model rats. Thus, we suppose the bifunctional inhibitor GR has good application prospects in the treatment of AD treatment.
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Scott LL, Downing TG. A Single Neonatal Exposure to BMAA in a Rat Model Produces Neuropathology Consistent with Neurodegenerative Diseases. Toxins (Basel) 2017; 10:E22. [PMID: 29286334 PMCID: PMC5793109 DOI: 10.3390/toxins10010022] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/23/2017] [Accepted: 12/27/2017] [Indexed: 12/11/2022] Open
Abstract
Although cyanobacterial β-N-methylamino-l-alanine (BMAA) has been implicated in the development of Alzheimer's Disease (AD), Parkinson's Disease (PD) and Amyotrophic Lateral Sclerosis (ALS), no BMAA animal model has reproduced all the neuropathology typically associated with these neurodegenerative diseases. We present here a neonatal BMAA model that causes β-amyloid deposition, neurofibrillary tangles of hyper-phosphorylated tau, TDP-43 inclusions, Lewy bodies, microbleeds and microgliosis as well as severe neuronal loss in the hippocampus, striatum, substantia nigra pars compacta, and ventral horn of the spinal cord in rats following a single BMAA exposure. We also report here that BMAA exposure on particularly PND3, but also PND4 and 5, the critical period of neurogenesis in the rodent brain, is substantially more toxic than exposure to BMAA on G14, PND6, 7 and 10 which suggests that BMAA could potentially interfere with neonatal neurogenesis in rats. The observed selective toxicity of BMAA during neurogenesis and, in particular, the observed pattern of neuronal loss observed in BMAA-exposed rats suggest that BMAA elicits its effect by altering dopamine and/or serotonin signaling in rats.
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Affiliation(s)
- Laura Louise Scott
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77 000, Port Elizabeth 6031, South Africa.
| | - Timothy Grant Downing
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77 000, Port Elizabeth 6031, South Africa.
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Amylin and its G-protein-coupled receptor: A probable pathological process and drug target for Alzheimer's disease. Neuroscience 2017; 356:44-51. [PMID: 28528968 DOI: 10.1016/j.neuroscience.2017.05.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/11/2017] [Accepted: 05/12/2017] [Indexed: 12/31/2022]
Abstract
G-protein-coupled receptors (GPCRs) are shown to be involved in Alzheimer's disease (AD) pathogenesis. However, because GPCRs include a large family of membrane receptors, it is unclear which specific GPCR or pathway with rational ligands can become effective therapeutic targets for AD. Amylin receptor (AmR) is a GPCR that mediates several activities, such as improving glucose metabolism, relaxing cerebrovascular structure, modulating inflammatory reactions and potentially enhancing neural regeneration. Recent studies show that peripheral treatments with amylin or its clinical analog, pramlintide, reduced several components of AD pathology, including amyloid plaques, tauopathy, neuroinflammation and other components in the brain, corresponding with improved learning and memory in AD mouse models. Because amylin shares a similar secondary structure with amyloid-β peptide (Aβ), I propose that the AmR/GPCR pathway is disturbed by a large amount of Aβ in the AD brain, leading to tau phosphorylation, neuroinflammation and neuronal death in the pathological cascade. Amylin-type peptides, readily crossing the blood-brain barrier (BBB), are the rational ligands to enhance this GPCR pathway and may exhibit utility as novel therapeutic agents for treating AD.
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Au NPB, Ma CHE. Recent Advances in the Study of Bipolar/Rod-Shaped Microglia and their Roles in Neurodegeneration. Front Aging Neurosci 2017; 9:128. [PMID: 28522972 PMCID: PMC5415568 DOI: 10.3389/fnagi.2017.00128] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/18/2017] [Indexed: 01/06/2023] Open
Abstract
Microglia are the resident immune cells of the central nervous system (CNS) and they contribute to primary inflammatory responses following CNS injuries. The morphology of microglia is closely associated with their functional activities. Most previous research efforts have attempted to delineate the role of ramified and amoeboid microglia in the pathogenesis of neurodegenerative diseases. In addition to ramified and amoeboid microglia, bipolar/rod-shaped microglia were first described by Franz Nissl in 1899 and their presence in the brain was closely associated with the pathology of infectious diseases and sleeping disorders. However, studies relating to bipolar/rod-shaped microglia are very limited, largely due to the lack of appropriate in vitro and in vivo experimental models. Recent studies have reported the formation of bipolar/rod-shaped microglia trains in in vivo models of CNS injury, including diffuse brain injury, focal transient ischemia, optic nerve transection and laser-induced ocular hypertension (OHT). These bipolar/rod-shaped microglia formed end-to-end alignments in close proximity to the adjacent injured axons, but they showed no interactions with blood vessels or other types of glial cell. Recent studies have also reported on a highly reproducible in vitro culture model system to enrich bipolar/rod-shaped microglia that acts as a powerful tool with which to characterize this form of microglia. The molecular aspects of bipolar/rod-shaped microglia are of great interest in the field of CNS repair. This review article focuses on studies relating to the morphology and transformation of microglia into the bipolar/rod-shaped form, along with the differential gene expression and spatial distribution of bipolar/rod-shaped microglia in normal and pathological CNSs. The spatial arrangement of bipolar/rod-shaped microglia is crucial in the reorganization and remodeling of neuronal and synaptic circuitry following CNS injuries. Finally, we discuss the potential neuroprotective roles of bipolar/rod-shaped microglia, and the possibility of transforming ramified/amoeboid microglia into bipolar/rod-shaped microglia. This will be of considerable clinical benefit in the development of novel therapeutic strategies for treating various neurodegenerative diseases and promoting CNS repair after injury.
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Affiliation(s)
- Ngan Pan Bennett Au
- Department of Biomedical Sciences, City University of Hong KongKowloon Tong, Hong Kong
| | - Chi Him Eddie Ma
- Department of Biomedical Sciences, City University of Hong KongKowloon Tong, Hong Kong.,Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong KongKowloon Tong, Hong Kong.,State Key Laboratory in Marine Pollution, City University of Hong KongKowloon Tong, Hong Kong
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38
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Chen H, Desai A, Kim HY. Repetitive Closed-Head Impact Model of Engineered Rotational Acceleration Induces Long-Term Cognitive Impairments with Persistent Astrogliosis and Microgliosis in Mice. J Neurotrauma 2017; 34:2291-2302. [PMID: 28288551 DOI: 10.1089/neu.2016.4870] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Repeated mild traumatic brain injury (rmTBI) has been identified by epidemiology as a high-risk factor for dementia at a later stage in life. Animal models to replicate complex features of human rmTBI and/or to evaluate long-term effects on brain function have not been established. In this study, we used a novel closed-head impact model of engineered rotational acceleration (CHIMERA) to investigate the long-term neuropathological and cognitive functional consequences of rmTBI. Adult C57BL/6 male mice were subjected to CHIMERA for 3 consecutive days 24 h apart. Functional outcomes were assessed by the beam walk and Morris water maze tests. Neuropathology was evaluated by immunostaining of glial fibrillary acidic protein (GFAP), amyloid precursor protein (APP), and ionizing calcium-binding adaptor molecule-1 (Iba-1), and by quantitative reverse transcription polymerase chain reaction (qRT-PCR) or Western blotting of GFAP, Iba-1, and tumor necrosis factor (TNF)-α. Repeated CHIMERA (rCHIMERA) resulted in motor deficits at 3 days, and in learning and memory impairments that were sustained up to 6 months post injury. GFAP and TNF-α gene expression was increased within a week, whereas astrogliosis and microgliosis were induced starting from day 1 up to 6.5 months after rCHIMERA with upregulated GFAP and Iba-1 protein levels. rCHIMERA also induced APP deposition from day 1 to day 7, but this diminished by 1 month. In conclusion, rCHIMERA produces long-lasting cognitive impairments with astrogliosis and microgliosis in mice, suggesting that rCHIMERA can be a useful animal model to study the long-term complications, as well as the cellular and molecular mechanisms, of human rmTBI.
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Affiliation(s)
- Huazhen Chen
- 1 Laboratory of Molecular Signaling, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health , Rockville, Maryland.,2 Center for Neuroscience and Regenerative Medicine at the Uniformed Services University of Health Sciences , Bethesda, Maryland
| | - Abhishek Desai
- 1 Laboratory of Molecular Signaling, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health , Rockville, Maryland
| | - Hee-Yong Kim
- 1 Laboratory of Molecular Signaling, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health , Rockville, Maryland
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39
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Fiala M, Kooij G, Wagner K, Hammock B, Pellegrini M. Modulation of innate immunity of patients with Alzheimer's disease by omega-3 fatty acids. FASEB J 2017; 31:3229-3239. [PMID: 28420693 DOI: 10.1096/fj.201700065r] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 04/05/2017] [Indexed: 02/06/2023]
Abstract
The innate immune system of patients with Alzheimer's disease and mild cognitive impairment (MCI) is deregulated with highly increased or decreased transcription of inflammatory genes and consistently depressed phagocytosis of amyloid-β1-42 (Aβ) by monocytes and macrophages. Current immune therapies target single mechanisms in the adaptive immune system but not innate immunity. Here, we summarize recent advances in therapy by ω-3, ω-6, and epoxy fatty acids; specialized proresolving mediators; and vitamin D3 that have proven immune effects and emerging cognitive effects in patients with MCI. The hypothesis of this approach is that macrophages of normal participants, but not those of patients with Alzheimer's disease and MCI, possess effective phagocytosis for Aβ and protect homeostasis of the brain and, furthermore, that defective MCI macrophages recover phagocytic function via ω-3. Recent studies of fish-derived ω-3 supplementation in patients with MCI have shown polarization of Apoε3/ε3 patients' macrophages to an intermediate M1-M2 phenotype that is optimal for Aβ phagocytosis and the stabilization of cognitive decline. Therefore, accumulating preclinical and preliminary clinical evidence indicates that ω-3 supplementation should be tested in a randomized controlled clinical trial and that the analysis should involve the apolipoprotein E genotype and intervening conditions during trial.-Fiala, M., Kooij, G., Wagner, K., Hammock, B., Pellegrini, M. Modulation of innate immunity of patients with Alzheimer's disease by omega-3 fatty acids.
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Affiliation(s)
- Milan Fiala
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, California, USA;
| | - Gijs Kooij
- Department of Molecular Cell Biology and Immunology, Vrije Universiteit (VU) Medical Center, Multiple Sclerosis Center Amsterdam, Amsterdam, The Netherlands.,Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Harvard Institutes of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Karen Wagner
- Department of Entomology, University of California, Davis, Davis, California, USA
| | - Bruce Hammock
- Department of Entomology, University of California, Davis, Davis, California, USA
| | - Matteo Pellegrini
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, California, USA
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40
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Spangenberg EE, Green KN. Inflammation in Alzheimer's disease: Lessons learned from microglia-depletion models. Brain Behav Immun 2017; 61:1-11. [PMID: 27395435 PMCID: PMC5218993 DOI: 10.1016/j.bbi.2016.07.003] [Citation(s) in RCA: 242] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/22/2016] [Accepted: 07/05/2016] [Indexed: 12/12/2022] Open
Abstract
Microglia are the primary immune cell of the brain and function to protect the central nervous system (CNS) from injury and invading pathogens. In the homeostatic brain, microglia serve to support neuronal health through synaptic pruning, promoting normal brain connectivity and development, and through release of neurotrophic factors, providing support for CNS integrity. However, recent evidence indicates that the homeostatic functioning of these cells is lost in neurodegenerative disease, including Alzheimer's disease (AD), ultimately contributing to a chronic neuroinflammatory environment in the brain. Importantly, the development of compounds and genetic models to ablate the microglial compartment has emerged as effective tools to further our understanding of microglial function in AD. Use of these models has identified roles of microglia in several pathological facets of AD, including tau propagation, synaptic stripping, neuronal loss, and cognitive decline. Although culminating evidence utilizing these microglial ablation models reports an absence of CNS-endogenous and peripheral myeloid cell involvement in Aβ phagocytosis, recent data indicates that targeting microglia-evoked neuroinflammation in AD may be essential for potential therapeutics. Therefore, identifying altered signaling pathways in the microglia-devoid brain may assist with the development of effective inflammation-based therapies in AD.
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Affiliation(s)
- Elizabeth E. Spangenberg
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders
| | - Kim N. Green
- Department of Neurobiology and Behavior, Institute for Memory Impairments and Neurological Disorders
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41
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Huynh TPV, Davis AA, Ulrich JD, Holtzman DM. Apolipoprotein E and Alzheimer's disease: the influence of apolipoprotein E on amyloid-β and other amyloidogenic proteins. J Lipid Res 2017; 58:824-836. [PMID: 28246336 DOI: 10.1194/jlr.r075481] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 02/25/2017] [Indexed: 12/13/2022] Open
Abstract
Alzheimer's disease (AD) is one of the fastest-growing causes of death and disability in persons 65 years of age or older, affecting more than 5 million Americans alone. Clinical manifestations of AD include progressive decline in memory, executive function, language, and other cognitive domains. Research efforts within the last three decades have identified APOE as the most significant genetic risk factor for late-onset AD, which accounts for >99% of cases. The apoE protein is hypothesized to affect AD pathogenesis through a variety of mechanisms, from its effects on the blood-brain barrier, the innate immune system, and synaptic function to the accumulation of amyloid-β (Aβ). Here, we discuss the role of apoE on the biophysical properties and metabolism of the Aβ peptide, the principal component of amyloid plaques and cerebral amyloid angiopathy (CAA). CAA is characterized by the deposition of amyloid proteins (including Aβ) in the leptomeningeal medium and small arteries, which is found in most AD cases but sometimes occurs as an independent entity. Accumulation of these pathologies in the brain is one of the pathological hallmarks of AD. Beyond Aβ, we will extend the discussion to the potential role of apoE on other amyloidogenic proteins found in AD, and also a number of diverse neurodegenerative diseases.
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Affiliation(s)
- Tien-Phat V Huynh
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University, St. Louis, MO 63110
| | - Albert A Davis
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University, St. Louis, MO 63110
| | - Jason D Ulrich
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University, St. Louis, MO 63110
| | - David M Holtzman
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University, St. Louis, MO 63110
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42
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Zuroff L, Daley D, Black KL, Koronyo-Hamaoui M. Clearance of cerebral Aβ in Alzheimer's disease: reassessing the role of microglia and monocytes. Cell Mol Life Sci 2017; 74:2167-2201. [PMID: 28197669 PMCID: PMC5425508 DOI: 10.1007/s00018-017-2463-7] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/07/2017] [Accepted: 01/11/2017] [Indexed: 01/03/2023]
Abstract
Deficiency in cerebral amyloid β-protein (Aβ) clearance is implicated in the pathogenesis of the common late-onset forms of Alzheimer’s disease (AD). Accumulation of misfolded Aβ in the brain is believed to be a net result of imbalance between its production and removal. This in turn may trigger neuroinflammation, progressive synaptic loss, and ultimately cognitive decline. Clearance of cerebral Aβ is a complex process mediated by various systems and cell types, including vascular transport across the blood–brain barrier, glymphatic drainage, and engulfment and degradation by resident microglia and infiltrating innate immune cells. Recent studies have highlighted a new, unexpected role for peripheral monocytes and macrophages in restricting cerebral Aβ fibrils, and possibly soluble oligomers. In AD transgenic (ADtg) mice, monocyte ablation or inhibition of their migration into the brain exacerbated Aβ pathology, while blood enrichment with monocytes and their increased recruitment to plaque lesion sites greatly diminished Aβ burden. Profound neuroprotective effects in ADtg mice were further achieved through increased cerebral recruitment of myelomonocytes overexpressing Aβ-degrading enzymes. This review summarizes the literature on cellular and molecular mechanisms of cerebral Aβ clearance with an emphasis on the role of peripheral monocytes and macrophages in Aβ removal.
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Affiliation(s)
- Leah Zuroff
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, 127 S. San Vicente, AHSP A8115, Los Angeles, CA, 90048, USA.,Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David Daley
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, 127 S. San Vicente, AHSP A8115, Los Angeles, CA, 90048, USA
| | - Keith L Black
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, 127 S. San Vicente, AHSP A8115, Los Angeles, CA, 90048, USA
| | - Maya Koronyo-Hamaoui
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, 127 S. San Vicente, AHSP A8115, Los Angeles, CA, 90048, USA. .,Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, USA.
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43
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Li C, Guo XD, Lei M, Wu JY, Jin JZ, Shi XF, Zhu ZY, Rukachaisirikul V, Hu LH, Wen TQ, Shen X. Thamnolia vermicularis extract improves learning ability in APP/PS1 transgenic mice by ameliorating both Aβ and Tau pathologies. Acta Pharmacol Sin 2017; 38:9-28. [PMID: 27694908 PMCID: PMC5220549 DOI: 10.1038/aps.2016.94] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 07/24/2016] [Indexed: 12/25/2022] Open
Abstract
Considering the complicated pathogenesis of Alzheimer's disease (AD), multi-targets have become a focus in the discovery of drugs for treatment of this disease. In the current work, we established a multi-target strategy for discovering active reagents capable of suppressing both Aβ level and Tau hyperphosphorylation from natural products, and found that the ethanol extract of Thamnolia vermicularis (THA) was able to improve learning ability in APP/PS1 transgenic mice by inhibiting both Aβ levels and Tau hyperphosphorylation. SH-SY5Y and CHO-APP/BACE1 cells and primary astrocytes were used in cell-based assays. APP/PS1 transgenic mice [B6C3-Tg(APPswe, PS1dE9)] were administered THA (300 mg·kg-1·d-1, ig) for 100 d. After the administration was completed, the learning ability of the mice was detected using a Morris water maze (MWM) assay; immunofluorescence staining, Congo red staining and Thioflavine S staining were used to detect the senile plaques in the brains of the mice. ELISA was used to evaluate Aβ and sAPPβ contents, and Western blotting and RT-PCR were used to investigate the relevant signaling pathway regulation in response to THA treatment. In SH-SY5Y cells, THΑ (1, 10, 20 μg/mL) significantly stimulated PI3K/AKT/mTOR and AMPK/raptor/mTOR signaling-mediated autophagy in the promotion of Aβ clearance as both a PI3K inhibitor and an AMPK indirect activator, and restrained Aβ production as a suppressor against PERK/eIF2α-mediated BACE1 expression. Additionally, THA functioned as a GSK3β inhibitor with an IC50 of 1.32±0.85 μg/mL, repressing Tau hyperphosphorylation. Similar effects on Aβ accumulation and Tau hyperphosphorylation were observed in APP/PS1 transgenic mice treated with THA. Furthermore, administration of THA effectively improved the learning ability of APP/PS1 transgenic mice, and markedly reduced the number of senile plaques in their hippocampus and cortex. The results highlight the potential of the natural product THA for the treatment of AD.
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Affiliation(s)
- Cong Li
- School of Life Sciences, Shanghai University, Shanghai 200444, China
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xiao-dan Guo
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Min Lei
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Jia-yi Wu
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Jia-zhen Jin
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xiao-fan Shi
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Zhi-yuan Zhu
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Vatcharin Rukachaisirikul
- Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
| | - Li-hong Hu
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Tie-qiao Wen
- School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Xu Shen
- School of Life Sciences, Shanghai University, Shanghai 200444, China
- Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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44
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Daria A, Colombo A, Llovera G, Hampel H, Willem M, Liesz A, Haass C, Tahirovic S. Young microglia restore amyloid plaque clearance of aged microglia. EMBO J 2016; 36:583-603. [PMID: 28007893 DOI: 10.15252/embj.201694591] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 11/24/2016] [Accepted: 11/28/2016] [Indexed: 11/09/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by deposition of amyloid plaques, neurofibrillary tangles, and neuroinflammation. In order to study microglial contribution to amyloid plaque phagocytosis, we developed a novel ex vivo model by co-culturing organotypic brain slices from up to 20-month-old, amyloid-bearing AD mouse model (APPPS1) and young, neonatal wild-type (WT) mice. Surprisingly, co-culturing resulted in proliferation, recruitment, and clustering of old microglial cells around amyloid plaques and clearance of the plaque halo. Depletion of either old or young microglial cells prevented amyloid plaque clearance, indicating a synergistic effect of both populations. Exposing old microglial cells to conditioned media of young microglia or addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) was sufficient to induce microglial proliferation and reduce amyloid plaque size. Our data suggest that microglial dysfunction in AD may be reversible and their phagocytic ability can be modulated to limit amyloid accumulation. This novel ex vivo model provides a valuable system for identification, screening, and testing of compounds aimed to therapeutically reinforce microglial phagocytosis.
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Affiliation(s)
- Anna Daria
- Biomedical Center (BMC), Ludwig-Maximilians Universität München, Munich, Germany
| | - Alessio Colombo
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
| | - Gemma Llovera
- Institute for Stroke and dementia research (ISD), Ludwig-Maximilians Universität München, Munich, Germany
| | - Heike Hampel
- Biomedical Center (BMC), Ludwig-Maximilians Universität München, Munich, Germany
| | - Michael Willem
- Biomedical Center (BMC), Ludwig-Maximilians Universität München, Munich, Germany
| | - Arthur Liesz
- Institute for Stroke and dementia research (ISD), Ludwig-Maximilians Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Christian Haass
- Biomedical Center (BMC), Ludwig-Maximilians Universität München, Munich, Germany .,German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Sabina Tahirovic
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
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45
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Solé-Domènech S, Cruz DL, Capetillo-Zarate E, Maxfield FR. The endocytic pathway in microglia during health, aging and Alzheimer's disease. Ageing Res Rev 2016; 32:89-103. [PMID: 27421577 DOI: 10.1016/j.arr.2016.07.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 07/01/2016] [Accepted: 07/05/2016] [Indexed: 12/14/2022]
Abstract
Microglia, the main phagocytes of the central nervous system (CNS), are involved in the surveillance and maintenance of nervous tissue. During normal tissue homeostasis, microglia migrates within the CNS, phagocytose dead cells and tissue debris, and modulate synapse pruning and spine formation via controlled phagocytosis. In the event of an invasion by a foreign body, microglia are able to phagocytose the invading pathogen and process it proteolytically for antigen presentation. Internalized substrates are incorporated and sorted within the endocytic pathway and thereafter transported via complex vesicular routes. When targeted for degradation, substrates are delivered to acidic late endosomes and lysosomes. In these, the enzymatic degradation relies on pH and enzyme content. Endocytosis, sorting, transport, compartment acidification and degradation are regulated by complex signaling mechanisms, and these may be altered during aging and pathology. In this review, we discuss the endocytic pathway in microglia, with insight into the mechanisms controlling lysosomal biogenesis and pH regulation. We also discuss microglial lysosome function associated with Alzheimer's disease (AD) and the mechanisms of amyloid-beta (Aβ) internalization and degradation. Finally, we explore some therapies currently being investigated to treat AD and their effects on microglial response to Aβ, with insight in those involving enhancement of lysosomal function.
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46
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Uchoa MF, Moser VA, Pike CJ. Interactions between inflammation, sex steroids, and Alzheimer's disease risk factors. Front Neuroendocrinol 2016; 43:60-82. [PMID: 27651175 PMCID: PMC5123957 DOI: 10.1016/j.yfrne.2016.09.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/10/2016] [Accepted: 09/14/2016] [Indexed: 12/19/2022]
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disorder for which there are no effective strategies to prevent or slow its progression. Because AD is multifactorial, recent research has focused on understanding interactions among the numerous risk factors and mechanisms underlying the disease. One mechanism through which several risk factors may be acting is inflammation. AD is characterized by chronic inflammation that is observed before clinical onset of dementia. Several genetic and environmental risk factors for AD increase inflammation, including apolipoprotein E4, obesity, and air pollution. Additionally, sex steroid hormones appear to contribute to AD risk, with age-related losses of estrogens in women and androgens in men associated with increased risk. Importantly, sex steroid hormones have anti-inflammatory actions and can interact with several other AD risk factors. This review examines the individual and interactive roles of inflammation and sex steroid hormones in AD, as well as their relationships with the AD risk factors apolipoprotein E4, obesity, and air pollution.
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Affiliation(s)
- Mariana F Uchoa
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA
| | - V Alexandra Moser
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA
| | - Christian J Pike
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA; Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA.
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47
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Echeverria V, Yarkov A, Aliev G. Positive modulators of the α7 nicotinic receptor against neuroinflammation and cognitive impairment in Alzheimer's disease. Prog Neurobiol 2016; 144:142-57. [DOI: 10.1016/j.pneurobio.2016.01.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 11/07/2015] [Accepted: 01/06/2016] [Indexed: 01/08/2023]
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48
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Amyloid-β42 protofibrils are internalized by microglia more extensively than monomers. Brain Res 2016; 1648:485-495. [PMID: 27531183 DOI: 10.1016/j.brainres.2016.08.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 08/09/2016] [Accepted: 08/13/2016] [Indexed: 12/22/2022]
Abstract
One pathological hallmark of Alzheimer's disease (AD) is the accumulation of amyloid-β peptide (Aβ) in the affected brain. While there are numerous deleterious effects of Aβ accumulation, there is general agreement that a sustained inflammatory response to aggregated Aβ contributes to progressive neurodegeneration in AD and microglial cells play a significant role in this process. Our laboratory and others have shown that small soluble aggregates of Aβ activate a microglia-mediated inflammatory response. One component of the response involves internalization of extracellular Aβ, and this process is likely very sensitive to Aβ structure. In this study we analyzed the proclivity of microglia for internalization of Aβ42 monomers and protofibrils using fluorescently-labeled Aβ. Both Aβ42 species were labeled directly via amino linkage with an Alexa Fluor 488 tetrafluorophenyl ester (AF488-TFP) and then isolated individually by chromatography. Aβ42 protofibrils retained their size and morphological properties after labeling but monomers had a much higher stoichiometry of labeling compared to protofibrils. Primary murine microglia internalized AF488-Aβ42 protofibrils rapidly and in significant amounts compared to AF488-Aβ42 monomers. Microglial internalization of protofibrils was dependent on time and concentration, and corresponded with tumor necrosis factor α secretion. In competition studies, unlabeled Aβ42 protofibril internalization, detected by immunostaining, did not diminish AF488-protofibril uptake. Internalized AF488-Aβ42 protofibrils were found widely dispersed in the cytosol with some lysosomal accumulation but little degradation. These studies highlight the sensitivity that microglia exhibit to Aβ structure in the internalization process and emphasize their affinity for soluble Aβ protofibrils.
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49
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Kajiwara Y, McKenzie A, Dorr N, Gama Sosa MA, Elder G, Schmeidler J, Dickstein DL, Bozdagi O, Zhang B, Buxbaum JD. The human-specific CASP4 gene product contributes to Alzheimer-related synaptic and behavioural deficits. Hum Mol Genet 2016; 25:4315-4327. [PMID: 27516385 DOI: 10.1093/hmg/ddw265] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 06/09/2016] [Accepted: 07/28/2016] [Indexed: 12/13/2022] Open
Abstract
Recent studies have indicated that innate immune signalling molecules are involved in late-onset Alzheimer's disease (LOAD) risk. Amyloid beta (Aβ) accumulates in AD brain, and has been proposed to act as a trigger of innate immune responses. Caspase-4 is an important part of the innate immune response. We recently characterized transgenic mice carrying human CASP4, and observed that the mice manifested profound innate immune responses to lipopolysaccharide (LPS). Since these inflammatory processes are important in the aetiology of AD, we have now analysed the correlation of expression of caspase-4 in human brain with AD risk genes, and studied caspase-4 effects on AD-related phenotypes in APPswe/PS1deltaE9 (APP/PS1) mice. We observed that the expression of caspase-4 was strongly correlated with AD risk genes including TYROBP, TREM2, CR1, PSEN1, MS4A4A and MS4A6A in LOAD brains. Caspase-4 expression was upregulated in CASP4/APP/PS1 mice in a region-specific manner, including hippocampus and prefrontal cortex. In APP/PS1 mice, caspase-4 expression led to impairments in the reversal phase of a Barnes maze task and in hippocampal synaptic plasticity, without affecting soluble or aggregated Aβ levels. Caspase-4 was expressed predominantly in microglial cells, and in the presence of CASP4, more microglia were clustered around amyloid plaques. Furthermore, our data indicated that caspase-4 modulates microglial cells in a manner that increases proinflammatory processes. We propose that microglial caspase-4 expression contributes to the cognitive impairments in AD, and that further study of caspase-4 will enhance our understanding of AD pathogenesis and may lead to novel therapeutic targets in AD.
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Affiliation(s)
| | - Andrew McKenzie
- Department of Genetics and Genomic Sciences.,Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, NY, USA
| | | | | | - Gregory Elder
- Department of Psychiatry.,Neurology Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA.,Department of Neurology
| | | | - Dara L Dickstein
- Department of Neuroscience.,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | - Bin Zhang
- Department of Genetics and Genomic Sciences.,Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, NY, USA
| | - Joseph D Buxbaum
- Department of Psychiatry .,Department of Genetics and Genomic Sciences.,Department of Neuroscience.,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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von Bernhardi R, Cornejo F, Parada GE, Eugenín J. Role of TGFβ signaling in the pathogenesis of Alzheimer's disease. Front Cell Neurosci 2015; 9:426. [PMID: 26578886 PMCID: PMC4623426 DOI: 10.3389/fncel.2015.00426] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 10/09/2015] [Indexed: 12/19/2022] Open
Abstract
Aging is the main risk factor for Alzheimer’s disease (AD); being associated with conspicuous changes on microglia activation. Aged microglia exhibit an increased expression of cytokines, exacerbated reactivity to various stimuli, oxidative stress, and reduced phagocytosis of β-amyloid (Aβ). Whereas normal inflammation is protective, it becomes dysregulated in the presence of a persistent stimulus, or in the context of an inflammatory environment, as observed in aging. Thus, neuroinflammation can be a self-perpetuating deleterious response, becoming a source of additional injury to host cells in neurodegenerative diseases. In aged individuals, although transforming growth factor β (TGFβ) is upregulated, its canonical Smad3 signaling is greatly reduced and neuroinflammation persists. This age-related Smad3 impairment reduces protective activation while facilitating cytotoxic activation of microglia through several cellular mechanisms, potentiating microglia-mediated neurodegeneration. Here, we critically discuss the role of TGFβ-Smad signaling on the cytotoxic activation of microglia and its relevance in the pathogenesis of AD. Other protective functions, such as phagocytosis, although observed in aged animals, are not further induced by inflammatory stimuli and TGFβ1. Analysis in silico revealed that increased expression of receptor scavenger receptor (SR)-A, involved in Aβ uptake and cell activation, by microglia exposed to TGFβ, through a Smad3-dependent mechanism could be mediated by transcriptional co-factors Smad2/3 over the MSR1 gene. We discuss that changes of TGFβ-mediated regulation could at least partially mediate age-associated microglia changes, and, together with other changes on inflammatory response, could result in the reduction of protective activation and the potentiation of cytotoxicity of microglia, resulting in the promotion of neurodegenerative diseases.
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Affiliation(s)
- Rommy von Bernhardi
- Laboratory of Neuroscience, Faculty of Medicine, Department of Neurology, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Francisca Cornejo
- Laboratory of Neuroscience, Faculty of Medicine, Department of Neurology, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Guillermo E Parada
- Laboratory of Neuroscience, Faculty of Medicine, Department of Neurology, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Jaime Eugenín
- Laboratory of Neural Systems, Faculty of Chemistry and Biology, Department of Biology, Universidad de Santiago de Chile Santiago, Chile
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